This invention relates to testing of microwave transistors (DUT) using automatic microwave impedance tuners used in order to synthesize known reflection factors (or impedances) at the input and output of the transistors.
A popular method for testing and characterizing microwave components (transistors) for low noise and high power operation is “source pull” and “load pull”. Load pull or source pull are measurement techniques employing microwave tuners and other microwave test equipment, such as noise receivers, mixers, low noise and power amplifiers, signal sources, power meters and directional couplers (FIG. 1). The microwave tuners in particular are used in order to manipulate the microwave impedance conditions under which the Device under Test (DUT, or transistor) is tested (FIG. 1). Pre-calibrated automatic tuners allow associating the reflection factors (Γ) with DUT performance (Gain, Power, Noise Figure . . . ) and enable circuit designers optimizing the matching networks for the DUT.
Many applications require impedance tuners to cover a very large (wideband) frequency range. In laboratory environment, in particular, test setups are expensive and applications may vary from the megahertz (MHz) frequency range to 50 or 100 gigahertz (GHz). A slide screw tuner (see ref. 1) being able to operate over such wide frequency ranges would then be required, but has not been known. In all cases, changing the frequency range of operation requires the (cumbersome) tuners to be swapped with tuners covering adjacent frequency ranges in order to cover the whole frequency band.